Security systems used to monitor premises and determine if the premises has been breached or an alarm condition exists are well known in the art. These systems typically include a control panel, a systems communications medium such as a data bus, and a number of security devices located throughout the premises for performing a certain function in the system. Security devices typically include glass break sensors, smoke detectors, fire detectors, motion sensors, door and window opening sensors, etc. Security devices also include peripherals such as dialers, keypads, display consoles, RF transmitters and receivers, etc. The control panel is typically configured to communicate with the security devices to collect and send information with these devices, such as when a user enters a “system arm” code in the keypad in order to arm the control panel and the security system.
Although security devices have in the past been typically wired to the system control panel, it has been increasingly common to utilize a wireless system wherein the need for a data bus or wired loop is eliminated (in whole or in part) by using radio frequency (RF) communications between components. In particular, it is desirable to use an RF transmitter in conjunction with a security device such as a motion detector to transmit RF signals to an RF receiver located near or integrated with the control panel for effecting wireless communications between the security device and the control panel. The RF receiver may also be interconnected to a wired bus or loop (to which the control panel is attached) so that a wireless link is utilized between the security device and the rest of the (wired) security system.
Data integrity is a particular concern with wireless security systems since there is no wired connection between the security device and the control panel. Methods have been used in the past, such as a cyclic redundancy check (CRC), in an attempt to provide for some error detection and/or correction in data transmissions. It is an object of the present invention to provide an improved methodology for ensuring error-free data transmissions between components of a security system.